JPH02277432A - Curvature measuring apparatus - Google Patents

Abstract

PURPOSE:To measure automatically a curvature radius of a main longitude of a sphere, etc., by calculating the curvature radius of a curved face to be detected from a projected straight line pattern corresponding to a straight line pattern of a reflected light selected by means of a masking device detected by means of a detecting device. CONSTITUTION:A cornea C to be examined is irradiated with a round light bundle with a specified radius and the reflected light is selectively passed through a straight line aperture A-C formed on a mask M in a distance l from the top Oc of the cornea and inclined at a specified angle to X0 axis and detects projected straight line A'-C' corresponding to a face D to be detected. From the points of intersection of each line with X and Y axes, xa1-xa3 and ya1-ya3, equations for the projected straight line A'-C' are determined. Two roots of the quadratic equation are obtd. from the length and the slope of the projected straight line and the curvature radii r1 and r2 of the first and the second main longitudes of the cornea C is obtd. from said two roots. It is thereby possible to measure automatically the curvature radius of a main longitude of a spheric face or a toric face.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the radius of curvature of a curved surface, and more specifically, an off-salmometer for measuring the radius of curvature of the main meridian of the cornea of the human eye, and a device for measuring the radius of curvature of a contact lens. This invention relates to a curvature measuring device that can be applied to a radius meter.

In this specification, the principles and embodiments of the present invention will be mainly explained with respect to an ophthalmometer, but the present invention is not limited thereto, and the present invention can be applied to a wide variety of surfaces such as spherical or toric curved surfaces having light reflectivity. The present invention can also be applied to a device that measures the radius of curvature of a radius line (hereinafter sometimes simply referred to as "radius of curvature").

The refractive power of the human cornea itself is approximately 80% of the total compressive power of the entire eye.
That is, it has a refractive power of about 45 Diopters, and about 75% of astigmatism in eyes is due to corneal astigmatism, that is, the anterior surface of the cornea is not spherical but has a toric surface shape. Furthermore, when prescribing a contact lens, the base curve needs to be prescribed based on the radius of curvature of the principal axis of the anterior surface of the cornea of the eye in which the contact lens is to be worn. From these points of view, it is important to measure the radius of curvature of the principal axis of the anterior surface of the cornea.

In response to this requirement, various types of off-salmometers have been put into practical use as devices for measuring the radius of curvature of the anterior surface of the cornea of the human eye. Both types of off-salmometers project one or more targets onto the cornea to be examined, and observe the size of the projected image or the position of its reflected image with the focal plane of an observation telescope. The radius of curvature and axis of corneal astigmatism of the cornea to be examined are measured from the amount of change in size or the amount of relative positional shift of the reflected image of the optotype.

In the ophthalmometer, especially when measuring the cornea of an astigmatic eye whose cornea has a toric surface shape, the radius of curvature of the first (Yayoi meridian) and second principal meridian (weak principal meridian) and at least one of the principal apertures are It is necessary to measure three measurable quantities of angle in the linear direction, and the conventional off-salmometer described above requires three stages of measurement to obtain these three measured values. However, the human eye is always accompanied by physiological eyeball vibrations, and longer measurement times result in vibrations in the projected image due to eyeball vibrations, resulting in measurement errors and the need for frequent alignment adjustment operations during measurement. There was a big problem.

For example, Japanese Patent Application Laid-open No. 56-18837, Japanese Patent Application Laid-Open No. 56-66235, or U.S. Pat.
An apparatus has been disclosed that detects a reflected image of a projected image from the cornea using a one-dimensional or two-dimensional position sensor, and measures the radius of curvature and principal axis angle of the cornea of the eye to be examined from the detected position.

However, like conventional off-salmometers, these devices use a telescope to form an image of the projected target reflected from the cornea, and to improve measurement accuracy, the focal length of the telescope must be increased. However, the drawback was that the Ikioi device became larger. Also, since it is an imaging type, it requires a focusing mechanism. Furthermore, alignment between the device and the cornea to be examined is performed using this focusing telescope, which results in inaccurate alignment, and does not lead to shortening of measurement time or complete automation.

U.S. Pat. No. 388 (1525) discloses an apparatus that uses a non-imaging optical system to measure the refractive properties of an optical system, mainly the spherical refractive power and cylindrical refractive power of a spectacle lens, and its axial angle. This device irradiates the lens of the eyeglass to be examined with a parallel light beam, selects the light beam deflected by the refractive characteristics of the lens to be examined using a mask means having a point aperture, and places it at a distance shorter than the focal length of the lens to be examined. The refractive characteristics of the lens to be tested are determined from the position of the projection point of the light beam passing through the point aperture onto the detector.

However, this US patent specification only discloses the measurement of refractive properties in a refractive optical system, and does not disclose or suggest anything about measuring the radius of curvature of the reflective curved surface of a reflective optical system. Furthermore, since this device uses a point aperture to detect refractive characteristics, it is necessary to use the above-mentioned flat image detector or TV camera as a detection means, which not only makes the device expensive but also If dirt, dust, etc. adhere to the lens, the optical system of the device, or the detection surface, if the light flux that should pass through the point aperture is blocked by the dirt, dust, etc., the refractive characteristics of the lens under test may not be measured. Was.

Therefore, the present invention solves the above-mentioned drawbacks of the conventional off-salmometer, and provides a curvature measurement device that can be applied to off-salmometers, radius meters, etc., and is capable of automatic measurement using a non-imaging optical system. This is what we intend to provide.

Another object of the present invention is to use a non-imaging optical system to reduce the size of optical components that need to be observed and operated by an examiner, such as an imaging telescope. It is an object of the present invention to provide a curvature measuring device that can automatically measure the radius of curvature of the principal radius of a spherical or toric surface without having any.

Yet another object of the present invention is to provide an automated system that can automatically output information for alignment between the curved surface to be inspected and the optical axis of the device, which conventional devices do based on standards, and that is easy to operate and shortens measurement time. An object of the present invention is to provide a curvature measuring device.

Yet another object of the present invention is that by increasing the amount of information in the masking means, it is possible to use a detection means that is cheaper than conventional off-thermometers as well as automatic lens meters, and it also prevents dust from entering the optical system and detection surface of the device. To provide a curvature measuring device capable of automatically measuring curvature, which is resistant to disturbance effects, highly accurate, and inexpensive, capable of measuring even in the presence of dust.

Incidentally, according to the present invention, there is provided an illumination optical system having a light source and a collimator means for converting light from the light source into a parallel light beam; and a light beam reflected by a curved surface to be inspected from the light beam from the illumination optical system is selected. At least 2 on the practical side for
a detection optical system comprising: a mask means having a straight line pattern configured to substantially intersect the straight lines of the book at at least one point; and a detection means for detecting reflected light selected by the mask means; calculation means for calculating the radius of curvature of the curved surface to be inspected from a linear projection pattern corresponding to the linear pattern of the reflected light detected by the detection means; both the linear pattern and the detection means are connected to the light source and the optical Provided are curvature measuring devices each disposed on mutually different planes that are conjugate to each other.

Note that in the present invention, a "substantive intersection" includes both an actual intersection and a virtual intersection.

Furthermore, "substantially on a surface" refers to a case where the detection means are actually arranged on one plane, and a case where the detection means located at different locations are arranged as if they were on a virtual plane, for example, by optical means. This includes both cases where

In the present invention, due to the above-mentioned structural features, compared to conventional curvature radius measuring devices, the device is smaller, the measurement time is shorter, it is resistant to disturbance effects, and the measurement accuracy is higher.
Furthermore, it is inexpensive and can automatically measure the radius of curvature of the curved surface to be tested. Furthermore, since alignment information can be automatically output, it is possible to further shorten measurement time and improve measurement accuracy.

These advantages of the present invention are that, especially when the present invention is applied to an off-salmometer, the off-salmometer has high measurement accuracy that is not affected by eye vibration, has a short measurement time, is small, and enables automatic measurement at low cost. can be provided.

Furthermore, if the present invention is applied to a so-called radius meter that measures the base curve or radius of curvature of the front surface of a contact lens, the target image can be compared to the surface of the contact lens.
Compared to the conventional radius meter, which focuses twice on the center of curvature and measures the radius of curvature of the base curve, etc. from the amount of movement of the objective lens at that time, it is possible to observe the target image and This eliminates the need for any microscope optical system for measurement, and therefore eliminates the need for diopter adjustment, which directly affects measurement accuracy, and enables automatic measurement without personal errors between operators, resulting in high measurement accuracy. , it is possible to provide a new type of radius meter that takes less time to measure.

Furthermore, the present invention can increase the information content of the mask means, and can use a detection means that is cheaper than conventional orthermometers or automatic lens meters, and can measure even if there is dirt or dust on the optical system or detection surface of the device. It is possible to provide a curvature measurement device that is resistant to disturbance effects, is highly accurate, and can perform automatic measurements at low cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The measurement principle and embodiments in which the present invention is applied to an off-salmometer for measuring the radius of curvature of the cornea will be described below with reference to the drawings.

FIG. 1 is a perspective view for explaining the measurement principle of the present invention, and FIG. 2 is a plan view thereof.

In these figures, the optical axis of the device is 0. X with origin at
Consider a 0Y o orthogonal coordinate system. The cornea C has its optical center O
c is shifted by E8 in the direction parallel to the X0 axis and by Ev in the direction parallel to the X0 axis, and the first principal radius (Yayoi radius) with a radius of curvature γ1 is at an angle ( 11. The radius of curvature of the second principal meridian (weak principal meridian) is γ2.The angle of the second principal meridian is θ+90°.

φ The cornea C to be examined is illuminated with a circular light beam having a radius of − as shown in FIG. Distance from! The light is selectively transmitted through linear apertures A, B, and C formed in a mask M separated from each other, and is projected onto a detection surface spaced a distance d from the mask M. These straight apertures A and B intersect each other at one point i, and the straight aperture C
intersects the straight-line frontage A at the intersection point j and the straight-line opening B at the intersection point, respectively. Linear frontage A is at an angle θ with respect to the X0 axis.

The straight opening B is inclined at an angle θ with respect to the X0 axis.
Assume that the slope is 2. Further, the intersecting angle of both straight apertures A and B is assumed to be θ. The length of the straight aperture A, i.e. the intersection i
The length between and j is 24, and the length of the straight opening B, that is, the length between intersection i and l.

shall be. Further, the slope of the linear aperture A is tanθ, =mA, and the slope of the linear aperture BΦ is tanθ2=m8.

In addition, the projection straight lines A', B', and C' corresponding to the linear apertures A, B, and C, respectively, on the detection surface are detected on the X-axis and on the X-Y orthogonal coordinate system provided on the detection surface. Although only the case of detecting the intersection of these projected straight lines on the Y axis will be described, it goes without saying that the entire detection surface may be scanned and detected. Further, when detection is performed on a surface, only two straight apertures A and B are required to be formed in the mask M, and the above-mentioned intersection j is the end point of the straight apertures A and B in this case.

Now, the intersections of the X and Y axes and the projection straight lines A', B' and C' are Xal Sxa, , xa3 and ya+, y
The equation of a straight line from ag and yaff can be determined by determining any two points among them, so the detection points 'Jar and
The equation of the projection straight line A' can be determined from a2, and similarly the equation of the projection straight line B' can be determined from the detection points xa and Vaz, and the equation of the projection straight line C' can be determined from the detection points Xa2 and yas. The length of the projected straight line is fA', the length of projected straight line B' is fB', or the slope of projected straight line A' is tanθ'
1 = mA', the slope of the projection straight line B' is jan, = m,
' are calculated from the equation of the projected line. This and the length of the linear frontage A of the above-mentioned mask M are 2^, its slope mA,
The length of straight opening B! 8. From its slope m, ψA' ml (ma ml) (+ 1) 2 ~ [mA
(mAffl11')+ψICmA'ml))
(+1)+(mA'-ms')=O-41
) is obtained, where ψ1, ψ8 are the distances! can be a constant determined by a known working distance detection means, or by using a relay optical system! The mask M may be set so that =0.

The angle θ of the first main radius line r1 is as follows. 2 roots of this quadratic equation. ．． 2. are the focal point F r+ of the first principal meridian of the cornea C from the mask M, and the second
It shows the distance to the focal point F of the main meridian. In general, the focal length of a spherical reflective optical system and its radius of curvature R are 5=R/
Since there is a relationship of 2, the corneal C from these 2iz, , Zz
The radii of curvature r+ and r2 of the first and second main meridians are respectively determined.

obtained as.

FIG. 3 is a perspective view showing a second embodiment of the measurement principle described above. In the embodiment shown in FIG. 3, projection straight lines A', B', and C' are detected from positions intersecting the two Y axes, that is, the Y axis and the Y2 axis on the X-7 plane of the detection surface.

As shown in Figure 3, the projected straight lines are )'l,'/z,
Intersect the Y, axis at y, y4, y5, y.

In Y! intersects the axis. Therefore, the equation of straight line B' is obtained from y2 and y&, and the equation of straight line A' is obtained from yl and y4.
The equation of the line C' is obtained from y, and the equation of the straight line C' is obtained from y and y. Based on the equations of these straight lines, the lengths of each of straight lines A' and B' are j! A', j!
11' and the slopes mA' and ml' can be found,
Also, the coordinates of ' can be found at the intersection points i' and j' of the straight lines.

FIG. 4 is a perspective view showing only the detection surface portion showing the third aspect of the measurement principle. This is an example when considering an oblique coordinate system x'-y' that intersects at an angle γ in the detection plane.

In this case, the projected straight line is the point X' l as shown in FIG.
% X' 2 , X' 3 and y'1・7' x
% 3” Intersect at s, straight line A from point XI and yl2
The equation of the line B' is obtained from the points X'l and yl, and the equation of the line C' is obtained from the points XI2 and V'x. Here, the oblique coordinate system X'-Y' on the detection surface
and the orthogonal coordinate system X-Y (or the orthogonal coordinate system X, -Y on the mask surface). The conversion to X-Y can be performed using the following equation, and then the shape characteristics of the cornea C to be examined can be calculated by using equations (1) to (3).

Alternatively, in calculating the radius of curvature r8 of the first main radial line, the radius of curvature r2 of the second main radial line, and the main radial angle (12),
Before irradiating the test cornea C with the illumination light beam, the illumination light beam was irradiated onto a reflective surface perpendicular to the optical axis of the device in the measurement optical path, and the reflected light beam was selectively transmitted through the linear apertures A, B, and C of the mask M. The projected straight lines A', B', and C' onto the detection plane are obliquely crossed by X'-
Detect in Y' coordinate system, length! 1.2. and the slope mA, m,
Calculate and use this value as the initial value. Next, place the cornea C to be examined in the measurement optical path, and similarly project straight lines A', B', and C'.
, and its length 1+A',j! 1′ and slope m
Calculate A'ml' and use the initial value! 7, el, mA, m
.

This is the II I wanted this time! a', j! s', ma', m
From s', the shape characteristics of the cornea to be examined, that is, the radius of curvature r3,
r2 and the main meridian angle θ can be measured. In this way, the present invention is a device that is independent of how the coordinate system is determined, and as described in the following embodiments, the linear position sensor is
'When arranged along each axis of the coordinate system, this arrangement position can be arbitrarily placed completely unrelated to the Xo Yo coordinate system on the mask, which is an extremely excellent feature in terms of device manufacturing and maintenance management.

Further, the straight line widths A, B, and C may have an imaginary intersection point 7 on the mask M instead of a substantial intersection point as shown in FIG. This means that the present invention provides linear apertures A, B, and C.
projection straight lines A', B', C' and X' on the detection surface.
- The intersection with each axis of the Y' coordinate system is detected, the equation of the projected straight line is obtained from this detected point, and the positions of the intersection points i'j' and k' are calculated based on this equation. Therefore, there is no need for the intersections i and J to actually exist as a pattern. In addition, straight openings A and B
,,C are linear openings A, B, and C, respectively, which do not need to form a triangle on the mask M, as shown in FIG.
By extending it, triangles i, j, and k can be virtually formed. These linear apertures A, B, and C are also subject to changes depending on the shape characteristics of the cornea C to be examined, similar to the above-mentioned principle.
Projection straight lines A'B' and C' are created on the detection plane. That is, as shown in FIG. 9, the linear apertures A, B, and C that create the virtual triangles i, j, and k in the Xo Yo coordinate system on the mask M are the oblique coordinates of X'-Y' on the detection surface. In the system X'l, X'Z
, X'3 and Y'+, z, y' 3 , and using the same principle as in FIG.
Therefore, from the equations of the calculated projection lines A', B', and C', the virtual triangle i' can be calculated.
j' and k' can be calculated. And virtual triangle i,
j, and the virtual triangle i'j', k' and the length fa
, j! ++, lA', 1m and slope mAs ms
, ms', , ms' and similarly calculate the radius of curvature rlsrZ and axis angle θ of the cornea to be examined using equations (1) to (3).
can be calculated.

The alignment amounts α and β are calculated and memorized in advance using triangles i and j formed by straight lines A, B, and C, as in equation (5), and then i is calculated from straight lines A', B', and C'. ′
By calculating j' and k' and finding the following, the horizontal and vertical alignment amounts α and β can be found as follows.

This shows that in the oblique coordinate system as shown in FIG. 6, it is possible to obtain the alignments 1-it α and β by performing calculations by performing the transformation of equation (4).

Detection points xa, , Xat, Xa3, Vat, Vat, ya of the projected straight line on the detection plane corresponding to the straight aperture of the mask M
:1%,)'l,)'2,)'3,y4,)'S,V
b.

Or X+', x, l, X3', y, + s
In order to determine which straight aperture each of Vt % V:l' corresponds to, it is necessary to change the width of the straight aperture, or to use two or three straight apertures instead of one straight aperture. You can use a method such as using groups. For example, as the linear openings on the mask, it is desirable to use an arrangement in which two sets of parallel linear openings are orthogonal to each other. If the projection of the intersection of the straight apertures is located on the coordinate axis, even if the widths of the straight apertures are different or a group of multiple straight apertures is used instead of one straight aperture, the Although it may be difficult to calculate the center position of the projected straight line, this problem can be solved by cutting one of the straight lines at the intersection of the straight lines in the straight line opening on the mask and providing an appropriate gap.

FIG. 10 is an optical layout diagram showing the first embodiment of the present invention. This embodiment is an off-salmometer that utilizes the measurement principle described above.

In this embodiment, a single linear position sensor is used as a detector by combining image low cheaters so that the optical conjugate images of the detector are obliquely crossed on the detection surface.
It is clear from the above principle explanation that the present invention is not limited to this, but can also be detected using a flat position sensor, two intersecting linear position sensors, or two parallel position sensors. .

As light sources for the illumination optical system 1, two infrared light emitting diodes 30 and 31 having different emission wavelengths are used. Light from the light emitting diode 30 passes through the dichroic surface 32a of the dichroic ink prism 32 and enters the condenser lens 7. On the other hand, the light from the light emitting diode 31 is reflected by the dichroic surface 32a and is also reflected by the condenser lens 7.
incident on .

The light emitted from the condenser lens 7 passes through the pinhole plate 10.
The light beam passes through the pinhole and is made into a parallel beam by the collimator lens 33 whose focal point is at this pinhole, and then the light beam is aligned with the optical axis of the device at 0. The light is reflected by the upwardly tilted micromirror 34 and irradiated onto the cornea C to be examined parallel to the optical axis 01. The fixation optical system 3 uses a half mirror 20 tilted in the illumination optical system 1 to illuminate the fixation target image onto the subject's eye.

The measurement optical system 2 includes, behind the first relay lens 14,
A mask plate 35 is arranged. In the mask plate 35, thick linear openings 25.26 are formed in parallel, and linear opening groups 27 and 28, each consisting of a set of three thin linear openings perpendicular to the parallel linear openings 25.26, are formed in parallel. It forms. The intersection point i of the thick straight aperture of this mask plate 35 and the group of three thin straight apertures, ! ! , is on the x0 axis, and the intersection j,
is on the Y0 axis. And their intersection points are shown in Figure 11 (
As shown in b), the straight aperture group 27 is cut by the straight apertures 25. The same applies to the linear aperture 26 and the linear aperture group 2. A conjugate image of this mask plate 35 by the relay lens 14 is formed at a position M in the figure. Further, a second relay lens group 36 is arranged behind the mask plate 35, and a gichroic mirror 37 having the same optical characteristics as the dichroic prism 32 is tilted behind it. This guichroic mirror 37 divides the measurement optical path into a first optical path 120 and a second optical path 121. The first optical path 120 includes mirror 1
22, a gicroic mirror 123, and a third relay lens 124. - On the other hand, the second optical path 121 is
It is composed of an image rotator 125, a mirror 126, a gicroic mirror 123, and a third relay lens 124. And behind the third relay lens 124,
A linear position sensor 38 is configured. This linear position sensor 38 includes the first relay lens 14,
The second relay lens group 36 and the third relay lens 124 create an optical conjugate image at the position shown in the figure, and
The image rotator 125 in the second optical path 121 acts as two virtual linear near sensors that intersect at a predetermined angle γ on the conjugate detection surface.

The parallel light beam from the light emitting diode 30 or 31 that exits the collimator lens 33 is reflected by the cornea C, and the curved surface characteristics of the cornea C to be examined, that is, the radius of curvature of the first and second principal meridians γ0, T
After being deflected according to t and the main meridian angle θ, it passes through the relay lens 14 and forms the straight aperture 25, 26, 27 of the mask plate 35.
and 28, and passes through the relay lens group 36, the first optical path 120 or the second optical path 121 to the linear sensor 38.
reach. At this time, the projection straight line is deformed according to the curved surface characteristics of the cornea C to be examined, and becomes, for example, as shown in FIG. 12.

Here, each projected line or group of projected lines and coordinate axes X', Y'
Intersection with X l', XZ', Xl, x4', y1'
, y2', y:l', y4' and performing necessary calculations according to the above equations (1) to (3), the curved surface characteristics of the cornea C to be examined can be obtained.

In the illustrated embodiment, two light emitting diodes 30 and 31 having different emission wavelengths are alternately flashed, and the light from one of the light emitting diodes 30 is transmitted from the illumination optical system 1 to the measurement optical system 2. The first optical path 1 passes through Mira=37
The light from the other light emitting diode 31 is reflected from the illumination optical system 1 by the guichroic mirror 37 of the measurement optical system 2, and is sent to the image lock. The light passes through a second optical path 121 having a theta 125 and reaches the linear sensor 38, where detection about the Y' axis is performed.

Next, referring to FIG. 13, the light emitting diode 30.3
A flip-flop 60 for driving this is connected to (2), and this flip-flop 60 is connected to a drive circuit 61
It is activated by a scan start pulse from . As the linear sensor 38, for example, a CC consisting of 1728 elements is used.
D is used, and its output is amplified by an amplifier 62 and given to a sample hold circuit 63. The output of the sample and hold circuit 63 is given to a comparator 64.
4, the reference value from the reference setter 65 is compared with the reference value 2.
It is converted into a value and produces an output cuff 01. The drive circuit 61 generates a scan start pulse 702 and a clock pulse 703,
These pulses are given to the sensor on day 3. 14th
The figure shows these pulses; (a) is the scan start pulse, (b) is the clock pulse, (C) is the output pulse of the sample and hold circuit 63, and (d) is the output cuff 01 of the comparator 64. show.

In such a configuration, when scanning is performed by the sensor 38, it is necessary to detect which position on the sensor 38 each projected straight line of the linear aperture has reached. To do this, it is only necessary to detect on which sensing element of the sensor 38 the center of the output pulse corresponding to the width of the projected straight line is located. The purpose is achieved by counting by pulses. A circuit for this purpose is shown in FIG.

In FIG. 15, the output cuff 01 from the comparator 64 is applied to a rising edge detector 40a and a falling edge detector 40b, and a scan start pulse 702 and a clock pulse 703 are applied to a counter 41. The counter 41 first receives the scan start pulse 7.
Clock pulse 703 after being cleared by 02
Count.

The output of the counter 41 is supplied to a latch circuit 44, and the latch circuit 44 receives the output 401 of the rising edge detector 40a.
latches the output of the counter 41.

The output of the latch circuit 44 at this time represents the position of the front end of the pulse L in FIG. 14 on the sensor 28, for example. The gate circuit 42 supplies a clock pulse to the counter 43, which has been cleared in advance by the scan start pulse 702, during the period when the output pulse 701 is "P1".The output of the gate circuit 42 is indicated by g in FIG. 16. Therefore, the output of the counter 43 shows a value equal to the projected straight line width projected onto the sensor 38. If the counter 43 is a binary counter, the least significant bit of the output of the gate circuit 42 is truncated to 1.
The value shifted by bits towards the lower bits and latch circuit 4
By adding the output of 4 in an adder 47, the center position of the projected straight line projected on the sensor 38 is obtained.

46 is a delay circuit, and the output 40 of the falling detector 40b
2 is delayed by Δt. This state is shown as f in FIG. 16. The output of the delay circuit 46 is sent to a counter decoder 48.
given to. This counter decoder 48 is connected to the adder 4
7 outputs are sequentially latched 191.192...
- This is for latching up to 198. Note that the output of the delay circuit 46 is also used to reset the counter 43.

With the above circuit, when one scan of the sensor 38 is completed, the latch 191 holds the center position of the first projected straight line that appears on the sensor, and the latch 192 holds the center position of the second projected straight line. be done. For example, when the sensor 38 is scanned along the Y' axis in FIG. 17, a signal corresponding to the eighth projection straight line appears on the sensor 38, as shown in C in FIG. Therefore, the latch circuit has 191
8 circuits from 198 to 198 are required.

In FIG. 15, 45 is a digital comparator which compares the output of the reference value generator 50 and the output of the counter 43 and supplies a comparison output to the latches 191-198. This is to determine whether the data represents the position of the intersection on the sensor due to a thick projected straight line among the projected straight lines or a thin projected straight line. Therefore, the output of each latch is sent to the determination circuit 51 together with information on the position of the center of the projected straight line and information on the size of the line width. The reason why the linear aperture of the mask is composed of one thick linear aperture and three thin linear apertures is to facilitate the discrimination of the projected straight line projected onto the sensor 38, as described above. This will be explained in detail using FIG. 18.

The 18th area is an enlarged view of the intersection of the projected straight lines.

25 is a thick projected straight line, 27 is three projected straight lines 27-1, which are thin enough to be easily distinguished from 25.
This is a group of projected straight lines consisting of 27-2 and 27-3.

Now, if the sensor 38 scans the pattern at position a or e, the center of the thick projection straight line 25 is determined to be the position of this projection straight line on the sensor, and the central projection straight line 27- 2 can be detected as the position of the projected straight line group 27. When the projection straight line is scanned at the position b, the output from the projection straight line 25.27-2.27-3 appears on the sensor 24, and at the position C, the output from the projection straight line 27-1.25.
27-3, at position d, the projection straight line 27-1.27-2
．． They are output in the order of 25. Therefore, when only two thin projected straight lines are projected onto the sensor, the position of the center of each straight line and group of straight lines can be detected and determined by performing the following determination.

(1) The center position of the sensor output based on the thick projection straight line is always set as the position of the projection straight line 25 detected on the sensor.

(2) When outputs from three thin projection straight lines appear in the sensor output, the position of the center of the intermediate projection straight lines is taken as the position of the projection straight line group 27 detected on the sensor.

(3) When only two trees are output by thin projection straight lines, (a) If the order is large, thin, thin, then the center of the first thin projection straight line, (b) Thin, thick, thin. (C) If the order is thin, thin, large, then the center of the second thin line is the position of the projected straight line group 27 detected on the sensor. shall be.

The above determination is made by the determination circuit 51 shown in FIG.

Although it is possible to configure the determination circuit 51 using random logic, a preferred configuration example is to use a microprocessor to perform the subsequent data processing including the determination circuit. It will be easy for those skilled in the art to use a microprocessor to make the above determinations.

Although the above explanation concerns the intersection between the projection straight line 25 and the projection straight line group 27, it goes without saying that other intersections can also be determined using the same method. Note that the sensor output corresponds to the four intersections in one scan, but by dividing it into two sections at the center position of the sensor and making the above judgment for each section, Y'+, V'z, y'3, y shown in Figure 17
′ on the sensor can be detected.

FIG. 19 shows an example of the overall configuration of an off-salmometer based on the measurement principle described above. In FIG. 19, 7 (10 is composed of the circuit shown in FIG. 13 and the optical system shown in FIG. 10. 1 (100 is composed of the circuit shown in FIG. The position on the sensor is input to the microprocessor 52.The microprocessor 52 includes a data memory section 53, a program memory section 54, a display interface section 55, a printer interface section 57, and an output for outputting the calculation result by the microprocessor. It is composed of a group of registers 291 to 295, but it is also easy to achieve such a configuration in the field of handling microprocessors.

With one scan of the first sensor, Y'l, Y'2, 'l'y
, V'a is obtained, in the next scan, mask 3
The light emitting diode illuminating 5 is switched. When the light emitting diode is switched, the emission wavelength is different, so the optical path by the optical system is switched, and equivalently, in Fig. 17, the sensor is
This means scanning along the ' axis. Therefore y'1, y'
2, x 13, y'4 on the sensor will be determined.

Once the position of the projection straight line on the sensor 38 is determined in this way, the curved surface characteristics of the cornea of the eye to be examined are calculated by the following calculation process.

(1) Find the equations of the projected straight line 25.26 and the projected straight line group 27.28, and calculate the slope m' of the projected straight line group 27 and the projected straight line 2.
6 is assumed to be m'8.

(n) Find the length of the projected straight line group 27 sandwiched between the projected straight lines 25 and 26, and calculate the length as y'. shall be.

(III) Projected straight line 2 sandwiched between projected straight line groups 27 and 28
Find the length of 6 and make it 2'8.

(IV) Calculation of alignment t-it α, β is performed by setting the respective coordinates of l to (y'1, y',) in Figure 17 i, j,
, (y'4, y',), (y'd, y m), alignment amount β (Y-axis direction) is obtained by extending equations (5) and (6) to the case of four intersections, and The above (
7) Calculate with the denominator of the formula as "4".

(V) A microprocessor performs arithmetic processing based on the above-mentioned equations to obtain desired curved surface characteristics.

The result obtained in this way is that the radius of curvature of the first principal meridian r
1, the second major radius of curvature r2, the major radius angle θ, and the alignment amounts α and β are outputted to the display 56, printer 58, and output registers 291 to 295 shown in FIG. 19. Note that by using a device capable of two-dimensional/dimensional display (for example, a CRT-display device, etc.) as the display 56, the alignment amounts α, β, and the main meridian angle θ are displayed as a two-dimensional pattern. I can do things. By doing this, there is an advantage that alignment between the cornea to be examined and the ophthalmometer can be easily and quickly performed.

Furthermore, if the alignment amount output register is connected to a movement mechanism that electrically and mechanically drives the off-salmometer housing to move it left, right, up and down, alignment can be automatically performed, as in the first embodiment described above. .

FIG. 20 is a partial optical arrangement diagram showing a second embodiment of the present invention. Components having the same functions as those in FIG. 10 are designated by the same reference numerals, and explanations thereof will be omitted. In this embodiment, instead of rotating the image using the image rotator 21 as shown in FIG. By changing the position to 301 (b), the sensor 38 is moved to 38 on the conjugate detection surface as shown in FIG.
The same effect can be obtained by moving the sensors 38 and 38' in parallel to the position 38' or by arranging the two sensors 38 and 38' in parallel.

When the sensor is at position 38, it detects the point 81% e4, and when it is at position 38', it detects points e'1 to e'4, and from this the equation of the projection straight line 25 to 28 can be calculated. , the curved surface characteristics of the cornea C to be examined can be measured by the same calculations as in the first embodiment.

FIG. 22 is an optical layout diagram showing a third embodiment of the present invention, and since the illumination optical system 1 and the fixation optical system 3 have the same configuration as in FIG. 10, they are shown in a simplified manner. Components similar to those in FIG. 10 are given the same reference numerals and their explanations will be omitted. In this embodiment, the mask 35 is divided into two masks 35-1.
．． 35-2, and the mask 35-1 has the markings shown in FIG.
) are formed into a group of linear apertures 27,28 in the mask 35-2, and are virtually combined into one on the conjugate mask surfaces by the relay lens 14. A microink mirror 37 is arranged behind the relay lens 14,
The optical path behind it is divided into a first optical path 120 and a second optical path 121. The aforementioned mask 35-1 is placed in the first optical path, and the mask 35-2 is placed in the second optical path 121, respectively. The light flux passing through the mask 35-1 is further divided into two by a half mirror 303, the reflected light flux is sent to the linear position sensor 38, and the transmitted light flux is sent to the linear position sensor 30.
2. Similarly, the light flux that has passed through the mask 35-2 is also reflected and transmitted by the half mirror 303, and enters the linear sensors 38 and 302, respectively. Here, the linear sensors 38 and 302 are arranged by the relay lens 14 so as to virtually intersect with each other within their conjugate detection planes. Due to the light emission from the light emitting diode 30, the linear sensor 38 detects X' 2 and X' 3 shown in FIG.
The linear sensor 302 detects y'2 and y'3. Next, when the light emitting diode 31 emits light, the near sensor 38
'1 and x'4 are detected, and the linear sensor 302 detects Y'z and Y'x.

Thereafter, the curved surface characteristics of the cornea to be examined are obtained by the same procedure as in the first embodiment described above.

Although the first to third embodiments described above use a fixedly arranged flat position sensor or one or more linear position sensors as a detector, the present invention is not limited to this. , at least one linear position sensor may be moved in parallel within a plane perpendicular to the optical axis 01 of the measurement optical system l, or may be rotated about the optical axis 01.

An example thereof is shown in FIG. The linear sensor 38 is rotated by a pulse motor 311 that is rotated by a pulse motor drive circuit 310 controlled by the microprocessor 1 (10) with the optical axis OI as the rotation axis.The linear sensor 38 is continuously rotated by this pulse motor 311. The sensor can be rotated by a predetermined angle to have the same function as a flat sensor on a conjugate detection surface, or can be rotated by a predetermined angle to have the same function as two intersecting linear sensors.

FIG. 24 is an optical layout diagram showing an embodiment in which the measurement principle of the present invention is applied to a radius meter for measuring the base curve or front curve of a contact lens. Components similar to those in the first embodiment described above are designated by the same reference numerals, and explanations thereof will be omitted.

When measuring the base curve of contact lens CL,
The contact lens is held by the circular tubular protrusion 601 of the contact lens holding means 6 (10) with the convex surface of the contact lens facing down.

In this embodiment, the conjugate detection surface by the relay lens 14 of the positional sensor 3B of the measurement system 2 is designed to be located inside the focal length fcL of the rear surface of the contact lens to be measured.

Although the measurement principle explained above and the example in which the mask means of each embodiment has a linear aperture that selectively transmits the luminous flux is shown, a reflective linear pattern that selectively reflects the luminous flux may be used instead. Needless to say, the same functions and effects as those of the present invention can be obtained.

Furthermore, the circuit that scans and drives the light-emitting element or the light-receiving element and processes the detected data is not limited to the above-mentioned circuit, but any circuit that can obtain the necessary data and process the above-mentioned arithmetic expression may be used. It will be apparent to those skilled in the art that various circuits could be designed.

[Brief explanation of drawings]

Fig. 1 is a perspective view for explaining the measurement principle of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a perspective view for explaining another aspect of the measurement principle, and Fig. 4 is a detection Figure 5 is a diagram showing an oblique coordinate system on a plane, Figure 5 is a diagram of projected straight lines appearing in oblique coordinates, Figure 6 is a diagram showing the relationship between oblique coordinates and orthogonal coordinates, and Figure 7 is a diagram showing virtual intersection points. FIG. 8 is a diagram showing another straight aperture of the mask and a projected straight line; FIG. 9 is a diagram showing a straight aperture having a virtual intersection and its projected straight line appearing on oblique coordinates. , FIG. 11(a) is a diagram showing an example of a linear aperture in a mask, FIG. 10 is an optical layout diagram showing the first embodiment of the present invention, and FIG. 11(b) is an illustration of an intersection of linear apertures in a mask. FIG. 12 is a diagram showing the relationship between the obliquely arranged linear sensor and the projected straight line, FIG. 13 is a block diagram showing a part of the detection circuit of the first embodiment, and FIG. 14 shows the detection pulse train. 15 is a block diagram showing the arithmetic processing circuit of the first embodiment, FIG. 16 is a diagram showing each output signal, and FIG. 17 is a diagram showing the relationship between the projection straight line and sensor scanning of the first embodiment. , FIG. 18 is a diagram showing scanning of the intersection of projected straight lines, FIG. 19 is a block diagram showing the entire electric circuit of the first embodiment, and FIG.
21 is a diagram showing the detection relationship between the projection straight line and the sensor in the second embodiment, and FIG. 22 is a diagram showing the third embodiment of the present invention. Optical arrangement diagram 12, figure 13, figure 21, figure 22, figure 23 showing an example of the optical arrangement.

Claims (17)

[Claims] (1) An illumination optical system having a light source and a collimator means for converting the light from the light source into a parallel light beam; comprising a mask means having a straight line pattern configured to substantially intersect at least two straight lines at at least one point on a surface, and a detection means for detecting the reflected light selected by the mask means. a detection optical system; a calculation means for calculating a radius of curvature of the curved surface to be inspected from a projected straight line pattern corresponding to the straight line pattern of the reflected light detected by the detection means; the mask means; A curvature measuring device characterized in that each of the devices is optically non-conjugate with the light source and is disposed on substantially different surfaces. (2) The curvature measuring device according to claim 1, wherein the straight line pattern includes at least three straight lines that substantially intersect at at least three points. (3) The straight line pattern is characterized in that the thickness or number of the straight lines constituting the straight line pattern or the selectivity of the reflected light are different from each other.
The curvature measuring device described in section 2). (4) The straight line pattern includes two sets each of which includes a first group of parallel straight lines each consisting of one straight line parallel to each other, and one set of three straight lines each substantially intersecting the first group of parallel straight lines. and a second parallel straight line group formed by forming a straight line group in parallel. Claim (2)
The curvature radius measuring device according to item (3) or item (3). (5) Claim (1) characterized in that the linear pattern is constituted by an opening formed in the mask means to selectively transmit the reflected light.
The curvature measuring device according to any one of items 1 to 4. (6) The curvature according to any one of claims (1) to (5), characterized in that the straight line pattern is formed by forming all the straight lines on one mask means. measuring device. (7) The curvature measuring device according to any one of claims (1) to (6), wherein the irradiation light beam is infrared light. (8) Claims (1) to (1), wherein the detection means is a flat position sensor.
7) The curvature measuring device according to any one of items 7). (9) The detection means is at least two linear position sensors that substantially intersect within the non-conjugate plane.
7) The curvature radius measuring device according to any one of items 7). (10) The detection means is at least two linear position sensors that are substantially parallel on the non-conjugate surface.
7) The curvature measuring device according to any one of items 7). (11) According to any one of claims (1) to (7), wherein the detection means is at least one linear position sensor that rotates on the non-conjugate surface. The described curvature radius measuring device. (12) The detection means is at least one linear position sensor, and includes a light beam rotation means for rotating the reflected light from the curved surface to be detected about the optical axis of the device. A curvature radius measuring device according to any one of claims (1) to (7). (13) Claims (1) to (7) characterized in that the detection means is at least one linear position sensor that moves in parallel within the non-conjugate plane.
The curvature measuring device according to any one of paragraphs. (14) A patent claim characterized in that the detection means is at least one linear position sensor and includes an image shift means for moving the reflected light in parallel within a plane perpendicular to the optical axis of the device. The curvature measuring device according to any one of the ranges (1) to (7). (15) Claim (1) characterized in that the detection optical system includes a relay optical means for forming an image of at least one of the detection means and the mask means on the non-conjugate surface. The curvature measuring device according to any one of items 1 to 14. (16) The detection optical system is characterized in that a reflection member having a reflection surface perpendicular to the illumination optical axis is insertably arranged between the detection surface and the mask means. The curvature measuring device according to any one of ranges (1) to (15). (17) Curvature measurement according to claim (15) or (16), characterized in that the optical axis of the relay optical means and the illumination optical axis are at least partially common. Device.